Spark preventing card screen

ABSTRACT

A card screen having a non-spark surface on at least a portion of the screen, manufactured either by forming the entire screen of a solid plastic material free from spark producing properties or by covering the blanks with a layer or laminate of plastic or other non-spark generating material at the point where the screen is set nearest the cylinders to prevent sparks resulting from engagement with the card screen by the cylinder teeth, which could possibly lead to fires in or beneath the carding machines.

United States Patent Jenkins, Jr.

1451 Aug. 22, 1972 [54] SPARK PREVENTING CARD SCREEN [72] Inventor: Robert Bain Jenkins, Jr., Gastonia,

[73] Assignee: Jenkins Metal Shops lnc., Gastonia,

[22] Filed: Sept. 3, 1970 [21] Appl. No.: 69,382

[52] US. Cl ..l9/95 [51] Int. Cl. ..D0lg 15/34 [58] Field of Search ..l9/95, 98, 105; 174/101.5

[56] References Cited UNITED STATES PATENTS 1,968,861 8/1934 Strang 19/98 3,348,268 10/1967 Jenkins, Sr. 19/95 Forsberg ..174/101.5 Elliott, Jr 19/98 Primary ExaminerDorsey Newton Attorney-Hunt, Heard & Rhodes [5 7 ABSTRACT A card screen having a non-spark surface on at least a portion of the screen, manufactured either by forming the entire screen of a solid plastic material free from spark producing properties or by covering the blanks with a layer or laminate of plastic or other non-spark generating material at the point where the screen is set nearest the cylinders to prevent sparks resulting from engagement with the card screen by the cylinder teeth, which could possibly lead to fires in or beneath the carding machines.

3 Claims, 6 Drawing Figures PATENTEDmszemn 3.685.099 v sum 1 or 2 O 2 INVENTOR.

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SPARK PREVENTING CARD SCREEN BACKGROUND OF THE INVENTION This invention relates to an improved card screen so constructed as to prevent the generation of sparks therefrom, which could conceivably cause fires because of the concentration of highly flammable fibers in the immediate vicinity.

In conventional carding practices, a lap of raw cotton fibers is introduced to the rear end of the carding machine, passes under a lickerin, from whence the fibers are transferred to a rapidly rotating main cylinder where they are aligned and attenuated. The fibers areformed into a web and transferred to the doffer cylinder from whence the web is condensed and finally removed from the front end of the carding machine as a rope of silver. A screen, comprising a series of spaced bars extending transversely across the path of the lap, surrounds the lower periphery of the main cylinder and has a rear portion thereof extending beneath a segment of the lickerin cylinder. The surfaces of both the lickerin cylinder and the main cylinder include a multitude of small teeth protruding therefrom to attenuate and align the fibers in the lap being processed therethrough. At both the front and rear ends of the main cylinder and at the front end of the lickerin plenum, the screens are set very close to their respective cylinders to facilitate transfer of the lap from cylinder to cylinder, to prevent excessive release of air therethrough and also to prevent a loss of spinnable fibers.

As a result of this close setting, lumps of fibers created by an uneven lap occasionally cause accidental contact between the teeth of the lickerin or main cylinder and the conventional metallic screen surface, generating sparks therefrom. These sparks could ignite the fibers or drop into the accumulation of lint beneath the cylinders creating a dangerous fire.

Laminated plates in themselves are not new to the carding industry as shown by the U. S. Pat. No. 3,462,799 to Elliott, Jr. The Elliott patent discloses improved front and rear knife plates which prevent damage to the cylinder teeth and in this respect comprise a metal, outer backing plate having a frangible, non-metallic inner lining formed of phenolic impregnated paper which is capable of pulverizing without shredding and without imbedding in the teeth of the card cylinder if contacted thereby.

The present invention on the other hand is foreign to this concept in that it contemplates on the surface of the screen the use of a non-frangible material that will, to some degree, become embedded in the teeth of the main cylinder or lickerin if engaged thereby. The material, which has non-spark properties, is used to form the card screen or, at least, to coat the surfaces thereof at the points where the screen is most likely to accidentally engage the cylinder, thereby eliminating the danger of sparks resulting from engagement with the screen by the cylinder or lickerin teeth.

In one preferred embodiment of the invention, therefore, a card screen is formed entirely from a solid plastic material as by molding, extruding or combinations thereof. A suitable plastic for solid screens would include polycarbonate having percent carbon black incorporated therein to eliminate static electricity and sold under the names LEXAN (a product of General Electric) and Mobay Merlon.

Another manner in which the invention can be practiced is to coat or line the end blanks of the screen adjacent the teeth of the cylinders with a spark prevention material. The lining is bonded to a recessed portion of the screen so that its exposed surface lies in the same plane as the surface of the screen bars, and is intended primarily for the purpose of preventing sparks upon engagement by the teeth of the lickerin or main cylinder.

It is therefore an object of the present invention to provide an improved card screen which is so con structed as to eliminate sparks, generated upon engagement of the screen by the teeth of the cylinders.

It is a further object of the present invention to provide a card screen having at least a portion thereof formed of a material which is non-spark generating when struck by a metal object.

Another object of the present invention is to provide a card screen formed entirely of a material that is nonspark generating if struck by a metal object.

It is yet a further object of the present invention to provide an improved card screen wherein the conventional end blanks are recessed and provided with a spark resistant coating or plastic molding or extrusion.

Other objects and advantages of the present invention will become apparent upon a reading of the following specification in view of the associated drawings, in which: I

FIG. 1 is an elevation view with'parts broken away showing a carding machine with a screen according to the present invention mounted thereon;

FIG. 2 is an enlarged perspective view illustrating a set of card screens of the type for which the present invention is adapted removed from the carding machine;

FIG. 3 is an enlarged perspective view, with parts broken away, illustrating the front end of the improved card screen;

FIG. 4 is a view similar to FIG. 3, except showing the rear end of the improved card screen and its juncture with the lickerin screen;

FIG. 5 is a sectional view taken substantially along lines 5--5 in FIG. 2 and illustrating the manner in which the end blanks are recessed so that the surface of the screen bars and coating occupy the same plane; and

FIG. 6 is a view similar to FIG. 5, except showing a card screen fonned entirely of a plastic, non-spark generating material.

Referring now to the drawings, there follows a more detailed description of the present invention which comprises in general a card screen S comprising a from screen F, a back screen B, and a lickerin screen L. The end portions 10, 30, and 50 of each of these screens, in the conventional carding arrangement are set within close tolerances closely adjacent the teeth of the main cylinder C and lickerin LC. Therefore, according to the present invention, these areas include a spark resistant surface of a suitable material such as a polyolefin.

Referring now to FIG. 2, in a conventional card screen S the front screen portion F comprises a pair of side ribs 12 and 14, a central rib 16 positioned therebetween, and a series of generally parallel, spaced bars 18 attached thereto and extending transversely to the path of the lap across the space between the ribs to provide an outlet for the lint-laden air, fly and debris to fall beneath the cylinders during the carding operation. A front blank 20 extends between side ribs 12 and 14 at the front end of the series of bars 18, and normally comprises a metallic sheet.

According to one embodiment of the present invention blank includes a metallic backing sheet 22 of such thickness that the surface adjacent the cylinder is recessed below the corresponding surface of bars 18 a distance approximately equal to the thickness of coating 24. As better shown in FIG. 3, the coating 24, which is formed of a flexible, spark resistant material such as a polyolefin or other suitable material, covers the surface of sheet 22, extends up around the apex 26 thereof and down a short distance around the back side 28. The polyolefin material is suitably bonded to the metallic backing sheet, by a suitable adhesive and the exposed surface thereof is coextensive with the inner surface of bars 18.

The back screen B comprises a pair of side ribs 32 and 34, a central rib 36, and a series of transversely extending bars 38 supported by and spanning the area therebetween similar to the manner in which bars 18 are positioned on front screen F. A rear blank 40, similar to front blank 20, is positioned between side ribs 32 and 34 at the rear end thereof and also includes a recessed metallic sheet 42 having a coating 44 of the spark resistant material adhered thereto. Coating 44 extends over the apex 46 of the blank and overlaps a short distance along the opposite side 48 (FIG. 4).

The lickerin screen L is smaller and abuts the rear edge 49 of the rear blank 40 of back screen B. As best shown in FIG. 2, screen L comprises a pair of side ribs 52 and 54 and a central rib 56 with bars 58 spanning the area between the side ribs at the rear end thereof. A front blank 60, similar to blanks 20 and 40, extends between the forward end of ribs 52 and 54, and comprises a recessed metallic sheet 62 covered by a coating 64 of spark resistant material in a manner similar to the coatings on blanks 20 and 40.

The coatings 24, 44 and 64 may be extended, if desired, to cover the bars 18 of front screen F, the bars 38 of rear screen B or the bars 58 of the lickerin screen L, however preferably the coating merely covers the end blanks of each screen, as they are the sections of the screen most closely adjacent the teeth of the cylinders and most likely to be contacted thereby. The lamination or coating thickness is preferably about the same thickness as the metal which in the illustrated embodiment is 0.025, therefore the metal backing sheets 22, 42, and 62 should be recessed approximately 0,025 in. below the operative surface of bars 18, 38 and 58.

Also, although polyolefin has been disclosed as the preferable coating material, it is obvious that other suitable coatings could be applied. For example, the end blank, rather than being formed as a laminated structure comprising a backing sheet and polyolefin coating, might also be formed as a solid plastic member suitably attached to the frame.

Moreover, according to a second embodiment the entire card screen can be formed of a plastic material including side ribs 34', screen bars 38', blanks as illustrated in FIG. 6. Such a construction eliminates the requirement of forming the metal screen with recessed backing sheets and subsequently bonding the spark resistant coating thereto.

Suitable plastics for solid screens and end blanks include polycarbonate having 20 percent carbon black incorporated therein to eliminate static electricity, sold under the names Lexan (a product of General Electric) and Mobay Merlon.

WHAT IS CLAIMED IS:

In a carding machine of the type including a lickerin, doffer, main cylinder with metallic clothing, and a screen mounted beneath and closely adjacent the surface of the main cylinder, said screen being of the type comprising a pair of side ribs, a plurality of bars extending between said side ribs transversely to the path of the lap through the card, and end blanks at each end of said screen, the improvement wherein at least a portion of the screen comprises a spark preventing material on at least the side thereof adjacent the main cylinder, said spark preventing material formed of a polycarbonate having incorporated therein at least twenty percent carbon black and being characterized as flexible, non-frangible, and non-spark generating if engaged by a sharp metallic object.

2. The improvement according to claim 1 wherein said end blanks comprise a metallic backing sheet having a coating of said spark preventing material on at least the surface thereof adjacent said cylinder, said backing sheet being recessed below the level of said bars a distance equal to the thickness of said coating, whereby said coating is coextensive with the exposed surface of said bars.

3. The improvement according to claim 1 wherein said side ribs, said bars and said end blanks are formed of said spark preventing material and molded together as an integral unit. 

1. In a carding machine of the type including a lickerin, doffer, main cylinder with metallic clothing, and a screen mounted beneath and closely adjacent the surface of the main cylinder, said screen being of the type comprising a pair of side ribs, a plurality of bars extending between said side ribs transversely to the path of the lap through the card, and end blanks at each end of said screen, the improvement wherein at least a portion of the screen comprises a spark preventing material on at least the side thereof adjacent the main cylinder, said spark preventing material formed of a polycarbonate having incorporated therein at least twentY percent carbon black and being characterized as flexible, non-frangible, and non-spark generating if engaged by a sharp metallic object.
 2. The improvement according to claim 1 wherein said end blanks comprise a metallic backing sheet having a coating of said spark preventing material on at least the surface thereof adjacent said cylinder, said backing sheet being recessed below the level of said bars a distance equal to the thickness of said coating, whereby said coating is coextensive with the exposed surface of said bars.
 3. The improvement according to claim 1 wherein said side ribs, said bars and said end blanks are formed of said spark preventing material and molded together as an integral unit. 